Check out studiodecor.co.uk They do huge ones, mines 10 x 20 and is brilliant. They also use a very heavy grade vinyl so heal marks, dents etc don't happen. I have used it on hard floors, carpets and even outside on grass with no problems. The only thing you need to bear in mind is they are heavy and need heavy duty stands.
I have a Lastolite white at my studio its 3 x 11 Metres its very hard wearing and produces excellent results. Get a good quality one and make sure if you are using them on a floor its a hard surface to avoid heel punctures.
Also make sure the floor its on is clean as grit will cause dents.
Don't bleach them unless you want a yellowish tinge to it!.
I have just ordered a good quality heavy duty backdrop support which can take vinyl as well as paper.
The studio has had a good sweep, but until I can move certain large objects the floor will have to wait for a good mop. Yes need it nice and clean for what ever backdrop I opt for.
Once I have my backdrop up, unless I'm changing rolls it will be staying up in the same place. Definitely not something I would want to be carrying around.